Transcript Airgas template

Chapter 16
Drugs Affecting Muscle Spasm
and Spasticity
Physiology
• The human body contains approximately 600 skeletal muscles.
• Skeletal muscle movement is voluntary.
• Striated muscle is composed of two contractile proteins.
• Muscle contraction is triggered by a sudden inflow of calcium
ions (Ca2+).
• In the resting state, the protein tropomyosin winds around
actin and covers the myosin-binding sites.
• Muscle contraction stops when Ca2+ is removed from the
immediate environment of the myofilaments.
Muscle Fibers
<Insert Figure 16.1>
Pathophysiology
• Muscle spasm
–
A muscle spasm is a sudden, violent involuntary contraction of a
muscle or group of muscles.
–
Spasms are related to a localized skeletal muscle injury or an
imbalance in electrolytes.
–
Tonic spasm is characterized by an unusually prolonged and
strong muscular contraction
• Spasticity
–
Spasticity is a condition in which certain muscles are
continuously contracted.
–
This contraction causes stiffness or tightness of the muscles.
–
Spasticity may be associated with spinal cord injury.
Centrally Acting Muscle Relaxants
• They act in the central nervous system (CNS).
• Prototype drug: cyclobenzaprine (Flexeril)
Cyclobenzaprine: Core Drug Knowledge
• Pharmacotherapeutics
– Manages muscle spasms associated with acute
musculoskeletal disorders
• Pharmacokinetics
– Administered: oral. Metabolism: liver. Excreted: urine
and bile. Onset: 1 hour. Duration: 12-24 hours.
• Pharmacodynamics
– Relieves muscle spasms through a central action
Cyclobenzaprine: Core Drug Knowledge
(cont.)
• Contraindications and precautions
–
Hyperthyroidism
–
14 days within use of MAOIs
• Adverse effects
– CNS depression and anticholinergic activity
– Arrhythmias, seizures, and MIs
• Drug interactions
– Tramadol, guanethidine, MAOIs, histamine-1 blocking
agents, and various herbal remedies
Cyclobenzaprine: Core Patient Variables
• Health status
– Assess past medical history and drug allergies
• Life span and gender
– Pregnancy category B
– Use precaution in administration to elderly
• Lifestyle, diet, and habits
– Avoid alcohol and other CNS depressant use
• Environment
– Assess environment where drug will be given
Cyclobenzaprine: Nursing Diagnoses and
Outcomes
• Risk for Injury related to CNS depressant effects and
potential cardiovascular effects.
– Desired outcome: the patient will remain free from
injury throughout therapy.
Cyclobenzaprine: Planning and
Interventions
• Maximizing therapeutic effects
– Take with full glass of water at evenly spaced
intervals
– Coordinate physical therapies with administration
• Minimizing adverse effects
– Assess for excessive sedation
– Caution the patient about the potential for orthostatic
hypotension
Cyclobenzaprine: Teaching, Assessment &
Evaluation
• Patient and family education
– Take medication as prescribed
– Explain adverse effects
– Do not take with other OTC medications
• Ongoing assessment and evaluation
– Evaluate patient’s safety
– Monitor level of sedation
Question
Cyclobenzaprine is chemically similar to what drug?
A. Adrenergic agents
B. Benzodiazepines
C. Tricyclic antidepressants
D. MAOIs
Rationale
Cyclobenzaprine is chemically similar to what drug?
C. Tricyclic antidepressants
Cyclobenzaprine is structurally similar to the tricyclic
antidepressants.
Centrally Acting Spasmolytics
• The centrally acting spasmolytics work in the CNS to
reduce excessive reflex activity
• Allow muscle relaxation
• Prototype drug: baclofen (Lioresal)
Baclofen: Core Drug Knowledge
• Pharmacotherapeutics
–
Relieves some components of spinal spasticity
• Pharmacokinetics
– Administered: oral. Distribution: crosses blood–brain
barrier. Metabolism: liver. Excreted: urine and bile. Peaks:
2–3 hours.
• Pharmacodynamics
– Acts specifically at the spinal end of the upper motor
neurons at GABAB receptors to cause hyperpolarization
Baclofen: Core Drug Knowledge
• Contraindications and precautions
– Hypersensitivity and spasticity of cerebral origin
• Adverse effects
– Drowsiness, weakness, dizziness and lightheadedness,
headache, nausea and vomiting, hypotension,
constipation, lethargy and fatigue, confusion, insomnia,
and increased urinary frequency
• Drug interactions
– CNS depressants or TCAs
Baclofen: Core Patient Variables
• Health status
–
Assess past medical history and allergies
–
Peform physical assessment
• Life span and gender
–
Older patients are more susceptible to sedation
• Lifestyle, diet, and habits
–
Caution the patient about the concurrent use of alcohol
• Environment
–
Assess environment where drug will be given. It isusually given
at the home.
Baclofen: Nursing Diagnoses and
Outcomes
• Acute Pain related to headache, muscle pain, GI
disturbances, or rash
– Desired outcome: the patient will be provided with
measures to decrease the discomfort of drug therapy
and the possibility of nonadherence.
• Risk for Disturbed Sensory Perception related to visual
changes, vestibular dysfunction, and somatosensory
changes
– Desired outcome: the patient will be protected
from injury if dizziness, weakness, visual changes, or
perceptual changes occur.
Baclofen: Planning and Interventions
• Maximizing therapeutic effects
– Take with full glass of water at evenly spaced
intervals
– If GI distress occurs, coordinate with meals
• Minimizing adverse effects
– Ensure patient safety
– Do not abruptly stop medication
Baclofen: Teaching, Assessment &
Evaluation
• Patient and family education
– Teach importance of patient safety
– Caution the patient about the concurrent use of alcohol
• Ongoing assessment and evaluation
– Monitor for the emergence of hallucinations or psychotic
episodes
– Assess for improved symptoms of spasticity
Question
• Baclofen therapy is effective at treating muscle spasms
due to a cerebral vascular accident.
– A. True
– B. False
Rationale
• Baclofen therapy is effective at treating muscle spasms
due to a cerebral vascular accident.
– B. False
– Baclofen therapy does not affect skeletal muscle
spasms resulting from CVA or parkinsonism. Baclofen
does not treat this condition because of the
mechanism of action of the drug.
Peripherally Acting Spasmolytics
• Peripherally acting spasmolytics relax muscles through
direct action on the skeletal muscle fibers.
• They do not interfere with neuromuscular
communication.
• They have no CNS effects.
• Prototype drug: dantrolene (Dantrium).
Dantrolene: Core Drug Knowledge
• Pharmacotherapeutics
– Used to treat malignant hyperthermia
• Pharmacokinetics
– Administered: oral or IV. Metabolism: liver. Excreted:
kidneys. Peak: 5 hours. T½: 7.3 hours.
• Pharmacodynamics
– Reduces the amount of Ca2+ released from the
sarcoplasmic reticulum, thereby relaxing the muscle
Dantrolene: Core Drug Knowledge (cont.)
• Contraindications and precautions
– Liver disease
• Adverse effects
– Muscle weakness, fatal hepatitis, seizures, and pleural
effusion with pericarditis
• Drug interactions
– CNS depressants, clofibrate, estrogens, verapamil,
and warfarin.
Dantrolene: Core Patient Variables
• Health status
– Assess past medical and physical assessment
• Life span and gender
– Consider the age before administration
• Lifestyle, diet, and habits
– Assess for lactose intolerance
• Environment
– Can cause photosensitivity
Dantrolene: Nursing Diagnoses and
Outcomes
• Risk for Injury related to muscular weakness
– Desired outcome: the patient will be injury free despite
muscular weakness.
• Risk for Disturbed Sensory Perception: Kinesthetic related to
dizziness, malaise, and fatigue
– Desired outcome: the patient will remain free of injury
from adverse effects.
• Disturbed Body Image related to drug-related dermatologic
effects
– Desired outcome: any adverse effects will be resolved by
the end of therapy.
Dantrolene: Planning and Interventions
• Maximizing therapeutic effects
– Administer with food or milk to avoid gastric distress
– Do not crush extended release capsule
• Minimizing adverse effects
– Provide for patient safety
– Advise the use of sunscreen
– Titrate dose to maximum effectiveness
Dantrolene: Teaching, Assessment, and
Evaluation
• Patient and family education
– Explain why the drug is prescribed
– Discuss adverse effects of drug
• Ongoing assessment and evaluation
– Monitor for improvement in symptoms of spasticity
and decrease in resistance to passive movement
– Monitor for adverse effects
Question
• Dantrolene is used to treat what condition(s)?
– A. Hypertensive crisis
– B. Malignant hyperthermia
– C. Pain associated with lumbar stenosis
– D. All of the above
Rationale
• Dantrolene is used to treat what condition(s)?
– B. Malignant hyperthermia
– IV dantrolene is the drug of choice for acute treatment of
malignant hyperthermia. Preoperatively, it can be used
orally or intravenously to prevent malignant hyperthermia
in patients considered at risk.